In the figure below a bar of length L, width w, and thickness d is positioned a distance h underneath a long straight wire that carries a large but unknown steady current Iwire (w is small compared to h, and h is small compared to the length of the long straight wire). The material that the bar is made of is known to have n positive mobile charge carriers (“holes”) per cubic meter, each of charge e, and these are the only mobile charge carriers in the bar. An ammeter measures the small current I passing through the bar. (a) Draw connecting wires from the voltmeter to the bar, showing clearly how the ends of the con- necting wires must be positioned on the bar in order to permit determining the amount of current in the long straight wire Iwire. If the voltmeter reading ∆V is positive, does the current in the long straight wire run to the left or to the right? Explain briefly. [2] (b) If the voltmeter reading is ∆V , what is the current in the long straight wire, Iwire? Express your
In the figure below a bar of length L, width w, and thickness d is positioned a distance h underneath
a long straight wire that carries a large but unknown steady current Iwire (w is small compared to h,
and h is small compared to the length of the long straight wire). The material that the bar is made
of is known to have n positive mobile charge carriers (“holes”) per cubic meter, each of charge e, and
these are the only mobile charge carriers in the bar. An ammeter measures the small current I passing
through the bar.
(a) Draw connecting wires from the voltmeter to the bar, showing clearly how the ends of the con-
necting wires must be positioned on the bar in order to permit determining the amount of current
in the long straight wire Iwire. If the voltmeter reading ∆V is positive, does the current in the
long straight wire run to the left or to the right? Explain briefly. [2]
(b) If the voltmeter reading is ∆V , what is the current in the long straight wire, Iwire? Express your
4
answer for the large current Iwire only in terms of the known quantities: h, L, w, d, n, Iammeter,
∆V , and known physical constants such as e.
Step by step
Solved in 3 steps with 1 images
